CN104011356B - The control gear of internal-combustion engine - Google Patents

Abstract

Provided is a control device for an internal combustion engine having an evaporative fuel passage for supplying evaporative fuel mixed gas, which is a mixed gas of evaporated fuel and air generated in a fuel tank, to an intake passage. Calculate the intake air amount corresponding to the state where the throttle valve is fully opened, that is, the fully open intake air amount, and calculate the theoretical intake air amount corresponding to the state where the exhaust gas of the internal combustion engine does not flow back into the combustion chamber from the fully open intake air amount and the intake pressure. The air-fuel ratio correction amount and its learning value are calculated according to the detected air-fuel ratio, and the reference intake air amount is calculated according to the intake pressure, the internal combustion engine speed, the air-fuel ratio correction amount and the learning value. A lower limit value of the detected intake air amount is set based on the reference intake air amount, and a limitation process of limiting the detected intake air amount to a range equal to or greater than the lower limit value is performed. The amount of evaporated fuel mixture supplied to the intake passage is calculated, the amount of intake air after the limitation process is corrected with the amount of evaporated fuel mixture, and the amount of intake air is calculated. The exhaust gas recirculation rate is calculated using the theoretical intake air volume and the intake gas volume.

Description

Control devices for internal combustion engines

technical field

The present invention relates to a control device for an internal combustion engine, and more particularly to a control device for an internal combustion engine that controls an exhaust gas recirculation rate indicating a ratio of exhaust gas (combustion gas) contained in gas sucked into a combustion chamber of the internal combustion engine.

Background technique

Patent Document 1 discloses a method of using an intake air amount sensor for detecting an intake air amount of an internal combustion engine for calculation of an exhaust gas recirculation rate. Due to the characteristic deviation of the intake air sensor and other factors, the detected intake air volume may deviate from the actual intake air volume. In the method of Patent Document 1, when there is such a detection deviation, the calculation accuracy of the exhaust gas recirculation rate decreases. .

Patent Document 2 discloses an air-fuel ratio control device that reduces the influence of detection variation of an intake air amount sensor. According to this control device, the air-fuel ratio feedback control amount is calculated based on the air-fuel ratio (oxygen concentration) detected in the exhaust system of the internal combustion engine, and the air-fuel ratio feedback control amount is used to perform feedback control of the air-fuel ratio. In the running state, the upper limit value of the detection value of the intake air sensor is changed according to the air-fuel ratio feedback control amount. Thereby, in particular, it is possible to prevent the control accuracy of the air-fuel ratio from deteriorating due to the influence of the wind direction reversal caused by the intake pulsation.

Prior Art Documents Patent Documents

Patent Document 1: International Publication No. WO2011/074302

Patent Document 2: Japanese Patent Laid-Open No. 2005-325762

Contents of the invention

The problem to be solved by the invention

In the case of a failure of the intake air sensor, or when there is a deviation of the exhaust gas recirculation passage and the evaporated fuel passage connected to the intake system of the internal combustion engine, even if the internal combustion engine is in an operating state other than a high-load operating state, the intake air The intake air volume detected by the air volume sensor also deviates from the actual intake air volume to a large extent, so that the calculation accuracy of the exhaust gas recirculation rate is reduced. Therefore, the control accuracy of the fuel supply control and the ignition timing control corresponding to the EGR rate calculated using the detected intake air amount deteriorates.

In fuel supply control, the actual air-fuel ratio can be maintained at a desired value in a stable operating state by performing air-fuel ratio feedback control, but control accuracy deteriorates in a transient operating state. On the other hand, in the ignition timing control, the detection error of the intake air amount becomes a cause of increased knocking and misfire even in a stable operating state. In the method shown in Patent Document 2, the above-mentioned abnormal state such as the deviation of the pipe is not taken into consideration, so there is room for improvement.

The present invention has been made with this point in mind, and an object of the present invention is to provide a control device for an internal combustion engine that appropriately limits the amount of detected intake air used in the calculation of the exhaust gas recirculation rate to a set lower limit value or more. The limiting process within the range can avoid the situation where the control accuracy of the control using the exhaust gas recirculation rate deteriorates to a large extent.

means to solve the problem

In order to achieve the above object, the present invention provides a control device for an internal combustion engine, which has a throttle valve (3) provided in the intake passage (2) of the internal combustion engine (1); An evaporative fuel passage (25) of the air passage (2), the evaporative fuel mixed gas is a mixed gas of air and evaporative fuel generated in a fuel tank that supplies fuel to the internal combustion engine. The control device is characterized in that it has: a rotation speed detection unit that detects the rotation speed (NE) of the internal combustion engine; an intake pressure detection unit that detects the intake air pressure (PBA) of the internal combustion engine; a full-open intake air amount calculation unit , which calculates the fully open intake air volume (GAWOT) according to the rotational speed (NE) of the internal combustion engine, and the fully open intake air volume (GAWOT) is the intake air volume corresponding to the state of the fully open throttle valve (3); theoretical an intake air amount calculation unit that calculates a theoretical intake air amount (GATH) corresponding to a state in which exhaust gas of the internal combustion engine does not flow back into the combustion chamber from the full-open intake air amount (GAWOT) and the intake pressure (PBA) ; the intake air amount detection unit, which detects the intake air amount (GACYLTMP) of the internal combustion engine; the air-fuel ratio detection unit, which detects the air-fuel ratio (KACT) in the exhaust passage (21) of the internal combustion engine; air-fuel ratio correction amount calculation A unit that calculates an air-fuel ratio correction amount (KAF) based on the detected air-fuel ratio (KACT); a learning value calculation unit that calculates a learning value (KREFX) of the air-fuel ratio correction amount (KAF); a reference intake air amount calculation unit , which calculates a reference intake air amount (GACYLREF) using the intake pressure (PBA) and engine speed (NE) and the air-fuel ratio correction amount (KAF) and learning value (KREFX); a lower limit value setting unit, which The lower limit value (GACLML) of the detected intake air amount (GACYLTMP) is set according to the reference intake air amount (GACYLREF); Limitation processing within a range above a limit value (GACLML); an evaporated fuel mixture amount calculation unit that calculates an evaporated fuel mixture amount (GPGC) supplied to the intake passage (2) via the evaporated fuel passage (25) ); an intake gas amount calculation unit that calculates an intake gas amount (GINGASCYL) by correcting the intake air amount (GAIRCYL) after the limitation process by using the evaporated fuel mixture gas amount (GPGC); and an exhaust gas recirculation calculation unit that The exhaust gas recirculation rate (REGRT) is calculated using the theoretical intake air amount (GATH) and the intake gas amount (GINGASCYL), and the internal combustion engine is controlled using the exhaust gas recirculation rate (REGRT).

According to this structure, the full-open intake air amount corresponding to the state where the throttle valve is fully opened is calculated from the engine speed, and the calculation is related to the complete absence of exhaust gas from the fully-open intake air amount and the intake pressure. The state of backflow corresponds to the theoretical intake air volume. And calculate the amount of evaporative fuel mixture supplied to the intake passage via the evaporative fuel passage, correct the intake air amount using the evaporative fuel mixture amount to calculate the intake gas amount, and calculate the EGR rate using the calculated intake gas amount and the theoretical intake air amount , and use the calculated exhaust gas recirculation rate for engine control. In addition, the air-fuel ratio correction amount is calculated based on the detected air-fuel ratio, and the learned value of the air-fuel ratio correction amount is calculated, and the reference intake air amount is calculated using the intake pressure, the engine speed, the air-fuel ratio correction amount and its learned value, and then based on the The reference intake air amount calculates the lower limit value of the intake air amount, and limits the detected intake air amount to a range equal to or greater than the lower limit value. Therefore, an accurate exhaust gas recirculation rate that also takes into account evaporated fuel mixture gas can be obtained by a relatively simple calculation, and the control accuracy of the internal combustion engine can be improved. Furthermore, setting of the lower limit value for detecting the amount of intake air is performed using the intake air pressure and the engine speed, and using the air-fuel ratio correction amount reflecting the actual air-fuel ratio of the air-fuel mixture combusted in the internal combustion engine and its learned value, so for example in When a failure of the intake air amount detection unit occurs, or when the piping of the evaporative fuel passage deviates, etc., it is possible to avoid the use of exhaust gas by properly performing a limitation process that limits the detected intake air amount to a range above the set lower limit value. The case where the accuracy of the internal combustion engine control of the recirculation rate deteriorates considerably.

In addition, it is preferable to further include an optimum ignition timing calculation unit for calculating an optimum ignition timing (IGMBT) for maximizing the output of the internal combustion engine based on the exhaust gas recirculation rate (REGRT), The control device performs ignition timing control of the internal combustion engine using the optimal ignition timing (IGMBT).

According to this configuration, the optimum ignition timing is calculated from the EGR rate, and the ignition timing control is performed using the calculated optimum ignition timing. Since it was confirmed that the relationship between the EGR rate and the optimum ignition timing is not affected by the operating phase of the intake valve and the presence or absence of external EGR, by setting the optimum ignition timing according to the EGR rate, it is possible to The optimum ignition timing suitable for the operating state of the internal combustion engine is easily calculated.

In addition, it is preferable to further have: a knock detection unit (14), which detects the knock of the internal combustion engine; a hysteresis correction amount calculation unit, which uses the knock detection unit (14) to detect the knock more frequently. The lag correction amount (DIGKCS) of the ignition timing is calculated in such a way that the lag correction amount (DIGKCS) of the ignition timing increases; and the fail-safe processing unit, which is when the lag correction amount (DIGKCS) reaches the lag limit value (DIGKMAX) , the control device uses the hysteresis correction amount (DIGKCS) to control the ignition timing of the internal combustion engine by replacing the limited intake air amount (GAIRCYL) with the reference intake air amount (GACYLREF).

According to this configuration, the retardation correction amount of the ignition timing is calculated so that the higher the detection frequency of knocking is, the larger the retardation correction amount of the ignition timing is, and the ignition timing control is performed using the retardation correction amount. When the hysteresis correction amount reaches the hysteresis limit value, fail-safe processing is performed to replace the intake air volume after the limit processing with the reference intake air volume, so in a state where the detected intake air volume is largely deviated from the actual intake air volume Under this condition, the occurrence of knocking can be reliably prevented.

In addition, it is preferable that the internal combustion engine has an exhaust gas recirculation channel (22) for recirculating exhaust gas from the exhaust channel (21) to the intake channel (2), and the control device further has: an estimated amount of return gas a calculating unit that calculates an estimated value of the amount of gas flowing into the intake passage (2) via the exhaust gas recirculation passage (22), that is, an estimated recirculation gas amount (GEGREXE); The air-fuel ratio determination parameter (KAFDET) obtained by dividing the correction amount (KAF) by the learned value (KREFX) falls within a prescribed range (RABNL ), it is determined that the exhaust gas recirculation channel (22) is abnormal, and the target value (REGREXCMD) of the external exhaust gas recirculation rate achieved via the exhaust gas recirculation channel (22) is greater than or equal to the specified value (REGREXTH), and the When the internal combustion engine is in a predetermined high-load operation state, the abnormality determination unit determines that the exhaust gas recirculation passage (22) is abnormal, and the hysteresis correction amount (DIGKCS) reaches the hysteresis limit value (DIGKMAX) , the reference intake air amount calculation unit corrects the reference intake air amount (GACYLREF) by multiplying the reference intake air amount (GACYLREF=GACYLREF2) by the air-fuel ratio determination parameter (KAFDET), the fail-safe process The unit replaces the intake air volume (GAIRCYL) after the restriction processing with the corrected reference intake air volume (GACYLREF).

According to this configuration, the estimated value of the amount of gas flowing into the intake passage via the exhaust gas recirculation passage, that is, the estimated return gas amount is calculated, and the air-fuel ratio determination parameter obtained by dividing the air-fuel ratio correction amount by the learned value is in accordance with the detected intake air. When the amount and the estimated return gas amount are set within the specified range, it is determined that the exhaust gas return passage is abnormal. When the target value of the external exhaust gas return rate achieved via the exhaust gas return channel is above the specified value, the internal combustion engine is operating at a specified high load, it is determined that the exhaust gas return channel is abnormal, and the hysteresis correction amount reaches the hysteresis limit value, pass The reference intake air amount is corrected by multiplying the reference intake air amount by the air-fuel ratio determination parameter, and a fail-safe process is performed in which the limit-processed intake air amount is replaced by the corrected reference intake air amount. In the case of deviation of the exhaust gas recirculation passage, the reference intake air amount calculated based on the intake pressure deviates from the actual intake air amount to a large extent, so it can be corrected by multiplying the air-fuel ratio determination parameter The reference intake air volume approximates the actual intake air volume with high precision. Therefore, by substituting the intake air amount after the restriction processing with the corrected reference intake air amount, it is possible to reliably detect the exhaust gas recirculation passage when the duct of the exhaust gas recirculation passage deviates and new gas flows from the exhaust gas recirculation passage to the intake passage. Prevent the occurrence of knocking. In addition, by using the air-fuel ratio determination parameter obtained by dividing the air-fuel ratio correction amount by the learned value, it is possible to perform high-accuracy correction by excluding the influence of characteristic deviations of the fuel injection valve and the intake air amount detection means.

In addition, the control device preferably further includes: an evaporated fuel concentration calculation unit that calculates an evaporated fuel concentration (KAFEVACT) in the evaporated fuel mixture; a corrected intake air amount calculation unit that uses (GPGC) and the new air amount (GPGACYL) in the evaporated fuel mixture calculated by the evaporated fuel concentration (KAFEVACT) corrects the intake air amount (GPGACYL), thereby calculating the corrected intake air amount (GAIRCYLC); and the knock limit an ignition timing calculation unit that calculates a knock limit ignition timing (IGKNOCK) corresponding to an occurrence limit of knock in the internal combustion engine based on the exhaust gas recirculation rate (REGRT) and the corrected intake air amount (GAIRCYLC), the The control device performs the ignition timing control using the retarded ignition timing of the optimum ignition timing (IGMBT) or the knock limit ignition timing (IGKNOCK).

According to this structure, the evaporated fuel concentration in the evaporated fuel mixture is calculated, the corrected intake air amount is calculated using the new air amount in the evaporated fuel mixture calculated from the evaporated fuel mixture gas amount and the evaporated fuel concentration to correct the intake air amount, and The knock-limited ignition timing is calculated from the exhaust gas recirculation rate and the corrected intake air volume. Since the knock-limited ignition timing has a high correlation with the exhaust gas recirculation rate, the knock-limited ignition timing can be calculated according to the exhaust gas recirculation rate, so that the output of the internal combustion engine within the range that can reliably avoid knocking can be accurately performed. Maximum ignition timing control. Also, when the evaporated fuel mixture is supplied to the intake passage via the evaporated fuel passage, the amount of new air drawn into the cylinder becomes a value obtained by adding the new air amount in the evaporated fuel mixture to the intake air amount, so it can be obtained by The exhaust gas recirculation rate and the corrected intake air volume are used to calculate the knock limit ignition timing and improve the calculation accuracy of the knock limit ignition timing.

In addition, there is also provided a control method of an internal combustion engine having: a throttle valve provided in an intake passage of the internal combustion engine; and an evaporated fuel passage supplying evaporated fuel mixture gas to the intake passage, The evaporated fuel mixed gas is a mixed gas of air and evaporated fuel generated in a fuel tank that supplies fuel to the internal combustion engine, and the method for controlling the internal combustion engine is characterized by the steps of: a) detecting the rotational speed of the internal combustion engine; b) detecting the intake air pressure of the internal combustion engine; c) calculating the fully open intake air volume according to the speed of the internal combustion engine, which is the intake air volume corresponding to the fully open state of the throttle valve; d) Calculate the theoretical intake air volume corresponding to the state in which the exhaust gas of the internal combustion engine does not flow back into the combustion chamber according to the fully open intake air volume and the intake pressure; e) detect the intake air volume of the internal combustion engine; f) Detect the air-fuel ratio in the exhaust channel of the internal combustion engine; g) calculate the air-fuel ratio correction amount according to the detected air-fuel ratio; h) calculate the learning value of the air-fuel ratio correction amount; i) use the intake pressure and the internal combustion engine speed and The air-fuel ratio correction amount and the learning value are used to calculate the reference intake air volume; j) set the lower limit value of the detected intake air volume according to the reference intake air volume; k) limit the detected intake air volume to Limiting processing in the range above the lower limit value; l) calculating the amount of evaporated fuel mixture supplied to the intake passage via the evaporated fuel passage; m) correcting the limiting the treated intake air volume, calculating an intake gas volume; and n) using the theoretical intake air volume and intake gas volume to calculate an exhaust gas recirculation rate, using the exhaust gas recirculation rate to control the internal combustion engine.

Description of drawings

FIG. 1 is a diagram showing the configuration of an internal combustion engine and its control device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a schematic configuration of the valve operation characteristic changing device shown in FIG. 1 .

FIG. 3 is a graph showing changes in the operating phase of the intake valve.

FIG. 4 is a diagram for explaining a calculation method of a total exhaust gas recirculation rate (REGRT).

FIG. 5 is a graph for explaining changes in the theoretical wide open air volume (GAWOT) corresponding to changes in atmospheric pressure.

FIG. 6 is a diagram for explaining intake air temperature correction.

FIG. 7 is a graph showing the relationship between the total exhaust gas recirculation rate (REGRT) and the optimum ignition timing (IGMBT).

FIG. 8 is a graph showing transition of mass burn ratio (RCMB).

FIG. 9 is a graph showing the relationship between the total exhaust gas recirculation rate (REGRT) and the EGR knock correction amount (DEGRT).

Fig. 10 is a flowchart of processing (first embodiment) for calculating the total EGR rate.

FIG. 11 is a flowchart of intake air amount (GAIRCYL) calculation processing executed in the processing of FIG. 10 .

FIG. 12 is a flowchart of processing for controlling the flow rate of evaporated fuel mixture.

FIG. 13 is a flowchart of PGCMD calculation processing executed in the processing of FIG. 12 .

FIG. 14 is a flowchart of processing for calculating an evaporated fuel concentration coefficient (KAFEVACT).

FIG. 15 is a flowchart of a process of calculating the ignition timing (IGLOG).

FIG. 16 is a flowchart of IGKNOCK calculation processing executed in the processing of FIG. 15 .

FIG. 17 is a flowchart of GAIRCYLC calculation processing executed in the processing of FIG. 16 .

FIG. 18 is a diagram for explaining settings of tables and maps referred to in the processing of FIG. 16 .

FIG. 19 is a graph showing the relationship between the charging efficiency (ηc) and the basic knock limit ignition timing (IGKNOCKB).

FIG. 20 is a time chart for explaining an example of control operations.

Fig. 21 is a time chart for explaining an example of control operation.

FIG. 22 is a flowchart showing a modified example of the processing in FIG. 11 .

Detailed ways

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing the configuration of an internal combustion engine and its control device according to an embodiment of the present invention, and FIG. 2 is a diagram showing the configuration of a valve operation characteristic changing device. In FIG. 1, for example, an internal combustion engine (hereinafter simply referred to as "engine") 1 having four cylinders has intake valves, exhaust valves, and cams for driving the intake valves and exhaust valves, and also has a valve action characteristic changing device. 40. The valve action characteristic changing device 40 has a valve action characteristic changing mechanism 42 as a cam phase changing mechanism that continuously changes the action phase of the cam driving the intake valve based on the crankshaft rotation angle. The operating phase of the cam that drives the intake valve is changed by the valve operating characteristic changing mechanism 42 to change the operating phase of the intake valve.

A throttle valve 3 is arranged in the intake passage 2 of the engine 1 . Also, a throttle opening sensor 4 that detects a throttle opening TH is coupled to the throttle valve 3 , and a detection signal thereof is supplied to an electronic control unit (hereinafter referred to as “ECU”) 5 . The actuator 7 that drives the throttle valve 3 is connected with the throttle valve 3, and the actuator 7 is controlled by the ECU 5 to act.

An intake air flow sensor 13 for detecting an intake air flow GAIR of the engine 1 is provided in the intake passage 2 . The detection signal of the intake air flow sensor 13 is supplied to the ECU 5.

An evaporative fuel passage 25 is connected to the downstream side of the throttle valve 3 of the intake passage 2 , and the evaporative fuel passage 25 is connected to a canister (not shown). A purge control valve 26 for controlling the flow rate of a mixed gas of evaporated fuel and air (evaporated fuel mixed gas, hereinafter referred to as “purge gas”) is provided in the evaporated fuel passage 25 . Purification control valve 26 is controlled its action by ECU 5. The canister stores evaporated fuel generated in a fuel tank that supplies fuel to the engine 1 , and when the purge control valve 26 is opened, purge gas is supplied from the canister to the intake passage 2 via the evaporated fuel passage 25 .

An exhaust gas recirculation passage 22 is provided between the exhaust passage 21 and the intake passage 2 , and the exhaust gas recirculation passage 22 is connected to the intake passage 2 on the downstream side of the throttle valve 3 . An exhaust gas return control valve 23 for controlling the exhaust gas return flow is arranged in the exhaust gas return channel 22, and the action of the exhaust gas return control valve 23 is controlled by the ECU 5.

An oxygen concentration sensor 24 (hereinafter referred to as "LAF sensor 24") is installed in the exhaust passage 21, and the oxygen concentration sensor 24 supplies a detection signal approximately proportional to the oxygen concentration (air-fuel ratio) in the exhaust gas to the ECU 5.

The fuel injection valve 6 is arranged between the engine 1 and the throttle valve 3 for each cylinder and slightly upstream of the intake valve not shown in the intake passage 2. While each injection valve is connected to a fuel pump not shown, It is electrically connected with the ECU 5 and controls the opening time of the fuel injection valve 6 through the signal from the ECU 5.

The spark plug 15 of each cylinder of the engine 1 is connected to the ECU 5, and the ECU 5 supplies an ignition signal to the spark plug 15 to control the ignition timing.

Installed downstream of the throttle valve 3 are an intake air pressure sensor 8 that detects an intake air pressure PBA and an intake air temperature sensor 9 that detects an intake air temperature TA. Furthermore, an engine coolant temperature sensor 10 for detecting an engine coolant temperature TW is attached to the main body of the engine 1 . Detection signals of these sensors are supplied to the ECU 5 .

The crank angle position sensor 11 that detects the rotation angle of the crankshaft (not shown) of the engine 1 and the cam angle position sensor 12 that detects the rotation angle of the camshaft on which the cam is fixed are connected to the ECU 5, and are connected to the rotation angle of the crankshaft and the rotation angle of the camshaft. A signal corresponding to the rotation angle is supplied to the ECU 5, wherein the above-mentioned cam drives the intake valve of the engine 1. The crank angle position sensor 11 generates one pulse (hereinafter referred to as "CRK pulse") and a pulse for determining a predetermined angular position of the crankshaft every fixed crank angle period (for example, a period of 6 degrees). In addition, the cam angle position sensor 12 generates a pulse (hereinafter referred to as "CYL pulse") at a predetermined crank angle position of a specific cylinder of the engine 1, and generates a pulse at the top dead center (TDC) when the suction stroke of each cylinder starts ( Hereinafter, it is referred to as "TDC pulse"). These pulses are used for various timing controls such as fuel injection timing and ignition timing, and detection of the engine speed (engine rotation speed) NE. Furthermore, the actual operating phase CAIN of the camshaft is detected from the relative relationship between the TDC pulse output from the cam angle position sensor 12 and the CRK pulse output from the crank angle position sensor 11 .

A knock sensor 14 that detects high-frequency vibration is installed at an appropriate position of the engine 1, and its detection signal is supplied to the ECU 5. In addition, an accelerator sensor 31 that detects the amount of depression of the accelerator pedal (hereinafter referred to as "accelerator pedal operation amount") AP of the vehicle driven by the engine 1, a vehicle speed sensor 32 that detects the running speed (vehicle speed) VP of the vehicle, and The atmospheric pressure sensor 33 of the atmospheric pressure PA is connected to the ECU 5. Detection signals of these sensors are supplied to the ECU 5 .

As shown in FIG. 2 , the valve action characteristic changing device 40 has: a valve action characteristic changing mechanism 42 which continuously changes the action phase of the intake valve, and an electromagnetic valve 44 which continuously changes the action phase of the intake valve. The opening can be changed continuously. The operating phase CAIN of the camshaft (hereinafter referred to as "intake valve operating phase CAIN") is used as a parameter indicating the operating phase of the intake valve. The lubricating oil in the oil pan 46 is pressurized by the oil pump 45 and supplied to the electromagnetic valve 44 . In addition, a specific structure of the valve operation characteristic changing mechanism 42 is disclosed in, for example, Japanese Patent Application Laid-Open No. 2000-227013.

By the valve operation characteristic changing mechanism 42, centering on the characteristic shown by the solid line L2 in FIG. The phase between the most retarded phases drives the intake valve. In the present embodiment, the intake valve operating phase CAIN is defined as an advance amount based on the most retarded phase.

In addition to the input circuit and the central processing unit (hereinafter referred to as "CPU"), and a storage circuit that stores calculation programs executed by the CPU, calculation results, etc., the actuator 7, the fuel injection valve 6, the spark plug 15, the exhaust gas recirculation control valve 23, and the drive signal supplied to the solenoid valve 44 output circuit and so on.

The CPU of ECU 5 performs ignition timing control, throttle valve 3 opening degree control, control of the amount of fuel supplied to the engine 1 (valve opening time of fuel injection valve 6 ) based on the detection signal from the above-mentioned sensor, and control valve based on exhaust gas recirculation. 23 exhaust gas recirculation control and control based on the valve action characteristics of the solenoid valve 44 .

The valve opening time TOUT of the fuel injection valve 6 is calculated by the following equation (1).

TOUT＝TIM×KCMD×KAF×KTOTAL (1)

Here, TIM is the basic fuel amount, specifically, the basic fuel injection time of the fuel injection valve 6, which is determined by searching the TIM table set according to the intake air flow rate GAIR. The TIM table is set so that the air-fuel ratio of the air-fuel mixture supplied to the engine becomes approximately the stoichiometric air-fuel ratio.

KCMD is a target air-fuel ratio coefficient set according to the operating state of the engine 1 . The target air-fuel ratio coefficient KCMD is proportional to the reciprocal of the air-fuel ratio A/F, that is, the fuel-air ratio F/A, and takes a value of 1.0 at the stoichiometric air-fuel ratio, so it is hereinafter referred to as "target equivalence ratio".

KAF is an air-fuel ratio correction coefficient that is controlled by PID (proportional-integral-derivative) control or Calculated using adaptive control of an adaptive controller (Self Tuning Regulator: self-tuning regulator).

KTOTAL is the product of other correction coefficients (correction coefficient KTW corresponding to engine cooling water temperature TW, correction coefficient KTA corresponding to intake air temperature TA, etc.) calculated based on various engine parameter signals.

Next, the outline of the calculation method of the exhaust gas recirculation rate in this embodiment will be described. In the following description, the dimensions of gas volumes such as “intake air volume” and “recirculated exhaust gas volume” are precisely the gas mass per TDC period (in a 4-cylinder engine, the period during which the crank angle rotates by 180 degrees).

4 is a diagram for explaining the calculation method of the total exhaust gas recirculation rate (hereinafter referred to as "total EGR rate") REGRT in this embodiment, showing the intake pressure PBA and the amount of gas sucked into the engine (air amount + recirculation The relationship between the exhaust gas amount) (the engine speed NE and the intake valve action phase CAIN are fixed). The total EGR rate REGRT is the ratio of the total return exhaust gas amount composed of the internal exhaust gas return flow and the external exhaust gas return flow through the exhaust gas return passage 22 to the total intake gas amount (theoretical intake air amount GATH) (refer to the following formula (12) (15) ). (a) of FIG. 4 corresponds to the state in which the purge control valve 26 is closed and the purge gas is not supplied to the intake passage 2 (hereinafter referred to as “purge stop state”), and (b) of FIG. 4 corresponds to the state in which the purge control valve 26 is opened, The state in which purge gas is supplied to the intake passage 2 (hereinafter referred to as "purge execution state") corresponds.

In FIG. 4 , the operating point PWOT represents an ideal operating point where external exhaust gas recirculation does not occur and internal exhaust gas recirculation does not exist, assuming that the throttle valve 3 is fully opened. At the operating point PWOT, the amount of intake air is maximized under the condition that the engine speed NE is constant. In addition, even in the state where the throttle valve 3 is fully opened, the residual gas rate (internal exhaust gas recirculation rate) never actually becomes "0". However, since the intake air pressure PBAWOT is almost equal to the atmospheric pressure PA, the internal exhaust gas recirculation rate is minimal. A straight line LTH passing through the operating point PWOT and the origin represents an ideal relationship between the amount of intake air and the intake pressure assuming no external exhaust gas recirculation and no internal exhaust gas recirculation. Hereinafter, this straight line LTH is referred to as "theoretical intake air amount straight line LTH". In addition, lines L11 and L12 respectively show the relationship when only the internal exhaust gas recirculation is considered and the relationship when both the internal exhaust gas recirculation and the external exhaust gas recirculation are considered. In addition, the lines L11 and L12 are not actually straight lines, but are shown as straight lines for convenience of description.

First, a method of calculating the total EGR rate REGRT in the purge stop state will be described with reference to FIG. 4( a ).

When the gas amount on the theoretical intake air amount straight line LTH corresponding to the state where the intake pressure PBA is PBA1 is "theoretical intake air amount GATH", the theoretical intake air amount GATH is expressed by the following equation (1). GAIRCYL in formula (11) is the intake air volume (fresh air volume), and GEGRIN, GEGREX, and GEGRT are the internal recirculation exhaust gas volume, external recirculation exhaust gas volume, and total recirculation exhaust gas volume, respectively.

GATH＝GAIRCYL+GEGRIN+GEGREX

=GAIRCYL+GEGRT (11)

Therefore, the total EGR rate REGRT is calculated by the following formula (12).

REGRT = GEGRT/GATH

=(GATH－GAIRCYL)/GATH (12)

On the other hand, in the purge execution state, the theoretical intake air amount GATH is given by the following equation (13). The GPGC in the formula (13) is the amount of purge gas supplied from the evaporated fuel passage 25 to the intake passage 2, and as shown in the following equation (14), the evaporated fuel amount GVAPOR contained in the purge gas and the fresh air contained in the purge gas The sum of GPGACYL (hereinafter referred to as "secondary air volume") is given. In addition, GINGASCYL in the formula (13) is the sum of the intake air amount GAIRCYL and the purge gas amount GPGC, and is hereinafter referred to as "the intake air amount GINGASCYL".

GATH＝GAIRCYL+GPGC+GEGRIN+GEGREX

=GINGASCYL+GEGRT (13)

GPGC＝GVAPOR+GPGACYL (14)

Therefore, the total EGR rate REGRT is calculated by the following formula (15).

REGRT = GEGRT/GATH

=(GATH－GINGASCYL)/GATH (15)

In addition, as described later, in controlling the ignition timing IGLOG, the corrected intake air amount GAIRCYLC calculated by adding the intake air amount GAIRCYL and the secondary fresh air amount GPGACYL is used (see FIG. 4( b )). .

If in the equations (13) and (15) corresponding to the purge execution state, if the amount of purge gas GPGC is set to "0", then the equations (11) and (12) corresponding to the purge stop state can be obtained. The equations (13) and (15) corresponding to the execution state are the basic equations and will be described below.

5 is a diagram for explaining changes in atmospheric pressure, and corresponds to a state where the full-open operating point PWOT1 is the operating point corresponding to the reference state, and the intake pressure PBA is the reference intake pressure PBASTD (for example, 100kPa (750mmHg)) . As the vehicle moves to a higher place, the atmospheric pressure drops, and the operating point PWOT1 moves on the theoretical intake air amount straight line LTH like the operating points PWOT2 and PWOT3. Curves L21 to L23 from the operating points PWOT1 to PWOT3 represent the intake gas amount GINGASCYL in consideration of internal exhaust gas recirculation (when external exhaust gas recirculation is not performed), respectively.

As described above, in the present embodiment, it is not necessary to change the theoretical intake air amount straight line LTH with respect to changes in atmospheric pressure, and it is possible to calculate an accurate total EGR rate REGRT even at high places.

However, it is necessary to perform air density correction in accordance with changes in the intake air temperature TA, and perform correction based on the following equation (16) based on the detected intake air temperature TA. TASTD in Equation (16) is the intake air temperature (for example, 25°C) in the reference state, and GAWOTSTD is the intake air amount corresponding to the full-open operating point PWOT in the reference state, which is hereinafter referred to as "the reference theoretical full-open air amount GAWOTSTD" . In addition, GAWOT is the intake air amount corresponding to the fully open operating point PWOT in the operating state of the detected intake air temperature TA, and is referred to as "theoretical fully open air amount GAWOT". "n" is a constant experimentally set to a value between "0" and "1", for example, set to "0.5".

$\mathrm{<span\; class="notranslate">\; GAWOT</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; GAWOTSTD</span>}<span\; class="notranslate">\; \&times;</span>{<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; TASTD</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 273</span>}}{\mathrm{<span\; class="notranslate">\; TA</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 273</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 16</span>}<span\; class="notranslate">\; )</span>$

The straight line LTHSTD shown in FIG. 6 is the theoretical intake air amount straight line in the reference state, and the straight line LTH is the theoretical intake air amount straight line corresponding to the detected intake air temperature TA. In addition, FIG. 6 corresponds to an example in which the detected intake air temperature TA is higher than the reference intake air temperature TASTD.

FIG. 7 is a graph showing the relationship between the full EGR rate REGRT and the optimum ignition timing IGMBT (the engine speed NE is fixed). The optimal ignition timing IGMBT is the ignition timing at which the engine output torque is maximum. In the figure, the symbols ● and ○ correspond to the operating state of the intake valve action phase CAIN of 0 degrees, the symbols ■ and □ correspond to the operating state of the intake valve action phase CAIN of 20 degrees, and the symbols ▲ and △ correspond to the intake valve action phase CAIN of 20 degrees. Corresponds to the operating state where the door action phase CAIN is 45 degrees. In addition, symbols ●, ■, and ▲ correspond to cases where no external exhaust gas recirculation is performed (internal exhaust gas recirculation only), and symbols ○, □, and △ correspond to cases where external exhaust gas recirculation is performed (internal exhaust gas recirculation + external exhaust gas recirculation).

From FIG. 7 , it can be confirmed that the relationship between the full EGR rate REGRT and the optimal ignition timing IGMBT does not depend on the operating phase CAIN of the intake valve or the presence or absence of external exhaust gas recirculation, and can be represented by a curve L31 . Therefore, by setting in advance an optimum ignition timing calculation map (IGMBT map) set based on the engine speed NE and the full EGR rate REGRT, it is possible to set the optimum ignition timing corresponding to all operating states. As a result, the workload for map setting can be greatly reduced.

FIG. 8 is a graph showing change characteristics of the mass combustion ratio RCMB of the air-fuel mixture sucked into the combustion chamber (the horizontal axis represents the crank angle CA). (a) of the figure shows the characteristics when the charging efficiency ηc is fixed and the total EGR rate REGRT is changed. Curves L41 to L43 correspond to operating states where the total EGR rate REGRT is 6.3%, 16.2%, and 26.3%, respectively. Curve L41 means the fastest burning speed. That is, it can be confirmed that the total EGR rate REGRT is a factor that changes the combustion rate of the air-fuel mixture.

On the other hand, (b) of FIG. 8 shows the characteristics (solid line, dotted line, and dashed-dotted line) when the total EGR rate is fixed and the charging efficiency ηc is changed. The solid line, dotted line, and dashed-dot line shown in the figure almost overlap, and it can be confirmed that even if the charging efficiency ηc is changed, the combustion rate of the air-fuel mixture hardly changes. Therefore, it can be confirmed that it is appropriate to set the optimum ignition timing IGMBT based on the total EGR rate REGRT instead of the charging efficiency ηc (intake fresh air amount).

9 is a graph showing the relationship between the full EGR rate REGRT and the EGR knock correction amount DEGRT (the engine speed NE is fixed). The EGR knock correction amount DEGRT is the ignition timing correction amount used to calculate the knock limit ignition timing IGKNOCK, and is suitable for making corrections corresponding to changes in the amount of recirculated exhaust gas, where the knock limit ignition timing IGKNOCK represents the knocking Generate limit. Symbols ○, □, and Δ shown in the figure represent data corresponding to states where the charging efficiency ηc is different, and it can be confirmed that they do not depend on the charging efficiency ηc. Therefore, the curve L51 can be used to represent the relationship between the full EGR rate REGRT and the EGR knock correction amount DEGRT in a state where the engine speed NE is fixed. Thus, the EGR knock correction amount DEGRT can be appropriately set by using the DEGRT map set based on the engine speed NE and the total EGR rate REGRT. In addition, the relationship represented by the curve L51 basically does not depend on the intake valve operation phase CAIN, but it may be necessary to perform correction corresponding to the intake valve operation phase CAIN due to variations in engine characteristics or the like. In this case, a plurality of tables corresponding to the intake valve operating phase CAIN may be provided, or correction corresponding to the intake valve operating phase CAIN may be performed.

FIG. 10 is a flowchart of processing for calculating the full EGR rate REGRT. This processing is executed by the CPU of the ECU 5 in synchronization with the generation of the TDC pulse.

In step S11, the GAWOTSTD map set based on the engine speed NE and the intake valve operating phase CAIN is retrieved, and the reference theoretical full-open air amount GAWOTSTD is calculated. In step S12, correction corresponding to the intake air temperature TA is performed based on the above formula (16), and the theoretical wide-open air amount GAWOT is calculated.

In step S13, the theoretical intake air amount GATH is calculated by using the detected intake air pressure PBA in the following equation (17).

GATH＝GAWOT×PBA/PBASTD (17)

In step S14, the GAIRCYL calculation process shown in FIG. 11 is executed, and the intake air amount GAIRCYL in one intake stroke of one cylinder is calculated from the detected intake air flow rate GAIR [g/sec]. In step S15, the purge gas flow rate QPGC calculated in step S68 of FIG. 13 is applied to the following equation (19) to convert it into the purge gas amount GPGC in one intake stroke of one cylinder. KC in Equation (19) is a conversion coefficient.

GPGC＝QPGC×KC/NE (19)

In step S16, the intake air amount GAIRCYL and the purge gas amount GPGC are applied to the following equation (20) to calculate the intake air amount GINGASCYL.

GINGASCYL＝GAIRCYL+GPGC (20)

In step S17, the total EGR rate REGRT is calculated by the above formula (15).

FIG. 11 is a flowchart of the GAIRCYL calculation process executed in step S14 of FIG. 10 .

In step S101, the detected intake air flow rate GAIR is applied to the following equation (21) to calculate the detected intake air amount GACYLTMP.

GACYLTMP＝GAIR×KC/NE (21)

In step S102, the detected intake air pressure PBA and the atmospheric pressure PA are applied to the following formula (22) to calculate the corrected intake air pressure PBAM. PAREF in the formula (22) is the reference atmospheric pressure set to, for example, 101.3 kPa.

PBAM＝PBA×PAREF/PA (22)

In step S103, a REGRIREF map is searched based on the engine speed NE and the corrected intake pressure PBAM, and a reference internal exhaust gas recirculation rate (hereinafter referred to as "reference internal EGR rate") REGRIREF is calculated. In the present embodiment, a plurality of REGRIREF maps are preset corresponding to a plurality of values of the intake valve operation phase CAIN, and selection and interpolation calculation of the map corresponding to the intake valve operation phase CAIN (current value) are performed. The reference internal EGR rate corresponds to the average internal EGR rate in a state where there is no external exhaust gas recirculation via the exhaust gas recirculation passage 22 .

In step S104, a first basic reference intake air amount GACYLREF1 is calculated by applying the reference internal EGR rate REGRIREF and the theoretical intake air amount GATH to the following equation (23). The first basic reference intake air amount GACYLREF1 corresponds to a reference value of the intake air amount in a state where external exhaust gas recirculation is not performed.

GACYLREF1＝(1－REGRIREF)×GATH (23)

In step S105, the first basic reference intake air amount GACYLREF1 and the EGR correction coefficient KEGR are applied to the following equation (24) to calculate the second basic reference intake air amount GACYLREF2. The second basic reference intake air amount GACYLREF2 corresponds to a reference value of the intake air amount in consideration of a state in which external exhaust gas recirculation is performed.

GACYLREF2＝GACYLREF1×KEGR (24)

Here, the EGR correction coefficient KEGR is a parameter equivalent to subtracting the target value REGREXCMD of the external exhaust gas recirculation rate set according to the engine operating state from "1" (1-REGREXCMD), and is set when the external exhaust gas recirculation is not performed. Set to "1".

In step S106, it is determined whether the KAF correction condition flag FKAFCND is "1". The KAF correction condition flag FKAFCND is set to "1" when the following conditions 1) to 4) are fully satisfied.

1) The engine 1 is in a predetermined high-load operation state (for example, an operation state with a charging efficiency of 60% or more).

2) The external exhaust gas recirculation rate target value REGREXCMD is equal to or greater than a predetermined value REGREXTH (for example, 0.15).

3) It is determined that the duct deviation of the exhaust gas recirculation passage 22 has occurred (hereinafter referred to as "secondary air inflow abnormality").

4) The knock lag correction amount DIGKCS of the ignition timing is equal to the maximum lag amount DIGKMAX.

Specifically, the above-mentioned condition 3) is judged as follows. It is judged whether the air-fuel ratio determination parameter KAFDET defined by the following formula (25) is within the predetermined abnormal range RABNL defined by (KAFX±DKAFX), and when the air-fuel ratio determination parameter KAFDET is within the predetermined abnormal range RABNL, it is determined that secondary Air inflow is abnormal.

KAFDET＝KAF/KREFX (25)

KREFX is the learned value of the air-fuel ratio correction factor KAF, which is the average value of the air-fuel ratio correction factor KAF calculated when the purge gas is not supplied to the intake passage 2 via the evaporated fuel passage 25 (a prescribed number of latest calculated values including the latest value moving average). However, when the intake air amount GAIRCYL is set to the upper limit value GACLMH or the lower limit value GACLML calculated in step S109, the learned value KREFX is held at the value before setting.

KAFX is a determination reference value calculated by the following formula (26), and DKAFX is a range setting value set to, for example, "0.1". This judging method is based on the fact that when secondary air inflow abnormality occurs, new gas that has not been detected by the intake air flow sensor 13 flows into the intake passage 2, so the air-fuel ratio judging parameter KAFDET and the following formula (26) The calculated judgment reference value KAFX is approximately equal.

KAFX＝(GACYLTMP+GEGREXE)/GACYLTMP

(26)

Here, GEGREXE is an estimated value of the amount of gas flowing into the intake passage 2 via the exhaust gas recirculation passage 22, that is, the estimated recirculation gas amount, and is calculated by subtracting the detected intake air amount GACYLTMP from the intake gas amount GGAS (the following formula ( 27)).

GEGREXE＝GGAS－GACYLTMP (27)

The intake gas amount GGAS is equivalent to the gas amount after subtracting the internal recirculation exhaust gas amount GEGRIN from the theoretical intake air amount GATH. By searching the preset GGAS table (equivalent to (b) in Figure 4) according to the corrected intake air pressure PBAM The line L11 shown) is calculated.

Normally, the answer in step S106 is negative (No), and the process proceeds to step S107, where the reference intake air amount GACYLREF is set as the second basic reference intake air amount GACYLREF2.

When the answer in step S106 is affirmative (Yes), that is, when the KAF correction condition flag FKAFCND is "1", the second basic reference intake air amount GACYLREF2, the air-fuel ratio correction coefficient KAF and the learned value KREFX are applied to the following equation (28): , to calculate the reference intake air volume GACYLREF.

GACYLREF＝GACYLREF2×KAF/KREFX (28)

In step S109, the upper limit value GACLMH and the lower limit value GACLML of the intake air amount are calculated for the theoretical intake air amount GATH and the reference intake air amount GACYLREF using the following equations (29) and (30), respectively.

GACLMH＝CLH×GATH (29)

GACLML＝CLL×GACYLREF (30)

Among them, CLH and CLL are constants for setting an allowable range, for example, they are set to values around "1.05" and "0.85", respectively.

In step S110, it is determined whether the hysteresis limit flag FKCSMAX is "1". The retardation limit flag FKCSMAX is set to "1" when the knock retardation correction amount DIGKCS of the ignition timing is equal to the maximum retardation amount DIGKMAX. When the answer at step S110 is affirmative (Yes), it is judged whether or not the detected intake air amount GACYLTMP is larger than the lower limit value GACLML calculated at step S109 (step S112 ). When the answer is negative (No), that is, when GACYLTMP≦GACLML, the intake air amount GAIRCYL is set as the reference intake air amount GACYLREF (step S114), and the switching flag FEATM indicating this is set to "1" (step S114 ). S115). On the other hand, when the answer in step S112 is affirmative (Yes), the switching flag FEATM is set to "0" (step S113), and the process proceeds to step S116.

If the answer at step S110 is negative (No) and the knock lag correction amount DIGKCS has not reached the maximum lag amount DIGKMAX, it is determined whether or not the switching flag FEATM is "1" (step S111 ). When the answer is affirmative (Yes), the process proceeds to step S112, and when the switching flag FEATM is "0", the process proceeds to step S116.

In steps S116 to S120, the limit processing for detecting the intake air amount GACYLTMP is performed to calculate the intake air amount GAIRCYL. That is, when it is detected that the intake air amount GACYLTMP is greater than the upper limit value GACLMH, the intake air amount GAIRCYL is set to the upper limit value GACLMH (steps S116, S117), and when the intake air amount GACYLTMP is detected to be smaller than the lower limit value GACLML, the intake air amount GAIRCYL is set to the upper limit value GACLMH. Set as the lower limit value GACLML (steps S118, S120), and when the detected intake air amount GACYLTMP is within the range of the upper and lower limits, set the intake air amount GAIRCYL as the detected intake air amount GACYLTMP (step S119).

Also, although not shown, immediately after the switching flag FEATM changes from "1" to "0", transition control is performed to gradually shift the intake air amount GAIRCYL from the reference intake air amount GACYLREF to the detected intake air amount GACYLTMP.

FIG. 12 is a flowchart of a process for performing purge gas flow rate control, that is, opening degree control of the purge control valve 26 . This process is executed by the CPU of the ECU 5 at predetermined intervals (for example, 80 msec).

In step S51, it is determined whether or not the purge execution flag FPGAACT is "1". The purge execution flag FPGAACT is set to “1” in the operation state of supplying purge gas to the intake passage 2 . When the answer in step S51 is negative (No), the purge control valve drive duty ratio DOUTPGC is set to "0" (step S52), and then the transitional control coefficient KPGT is set to a predetermined initial value KPGTINI (<1.0) ( Step S53). The transient control coefficient KPGT is a coefficient for restricting the flow rate of the purge gas when the purge gas supply is initially started, and is set to increase as time elapses before reaching "1.0" after the purge gas supply starts (refer to FIG. 13 Steps S65~S67).

When the answer in step S51 is affirmative (Yes), that is, when the purge gas is supplied, it is judged whether or not the fuel cut flag FFC is "1" (step S54). The fuel cut flag FFC is set to "1" in the operating state in which fuel supply to the engine 1 is temporarily stopped. When the fuel cut flag FFC is "1", the transient control coefficient KPGT is set to a predetermined initial value KPGTINI, and the purge control valve driving duty ratio DOUTPGC is set to "0" (steps S55, S56).

When the answer at step S54 is negative (No), the PGCMD calculation process shown in FIG. 13 is executed to calculate the target driving duty ratio PGCMD (step S57 ). In step S58, the purge control valve drive duty ratio DOUTPGC is set to the target drive duty ratio PGCMD. In step S59, the purge gas flow rate QPGC and the basic purge gas flow rate QPGCBASE calculated in the process of FIG. 13 are applied to the following equation (31) to calculate the purge gas flow rate ratio QRATE.

QRATE＝QPGC/QPGCBASE (31)

FIG. 13 is a flowchart of the PGCMD calculation process executed in step S57 of FIG. 12 .

In step S61, the basic purge gas flow rate QPGCBASE is calculated by using the detected intake air flow rate GAIR in the following equation (32). KQPGB in the formula (32) is a prescribed target purification rate.

QPGCBASE＝GAIR×KQPGB (32)

In step S62, it is determined whether the basic purge gas flow rate QPGCBASE is greater than the upper limit value QPGMAX, and if the answer is negative (No), the target purge gas flow rate QPGCMD is set as the basic purge gas flow rate QPGCBASE (step S63). When the basic purge gas flow rate QPGCBASE is greater than the upper limit value QPGMAX, the target purge gas flow rate QPGCMD is set to the upper limit value QPGMAX (step S64).

In step S65, the transient control coefficient KPGT is increased by a predetermined amount DKPGT (<1.0). In step S66, it is judged whether the transient control coefficient KPGT is greater than "1.0", and if the answer is negative (No), the process proceeds directly to step S68. When the answer in step S66 is affirmative (Yes), the transient control coefficient KPGT is set to "1.0" (step S67), and the process proceeds to step S68.

In step S68, the target purge gas flow rate QPGCMD and the transient control coefficient KPGT are applied to the following equation (33) to calculate the purge gas flow rate QPGC.

QPGC＝QPGCMD×KPGT (33)

In step S69, the purge gas flow rate QPGC is applied to the following equation (34), and the purge gas flow rate QPGC is converted into the target driving duty ratio PGCMD. KDUTY is a prescribed conversion coefficient, and KDPBG is a differential pressure coefficient set according to the differential pressure between the intake pressure PBA and the atmospheric pressure PA.

PGCMD＝QPGC×KDUTY/KDPBG (34)

According to the processing in FIG. 13, it can be seen that the purge gas flow rate ratio QRATE calculated in step S59 of FIG. 12 is smaller than “1.0” when the transition control coefficient KPGT is smaller than “1.0” and the basic purge gas flow rate QPGCBASE is larger than the upper limit value QPGMAX. The value of , otherwise takes "1.0".

14 is a flowchart of a process for calculating an evaporated fuel concentration coefficient KAFEVACT representing the evaporated fuel concentration in the purge gas. This process is executed by the CPU of the ECU 5 at predetermined intervals (for example, 80 msec).

In step S71, it is determined whether or not the feedback control flag FAFFB is "1". The feedback control flag FAFFB is set to "1" when the air-fuel ratio feedback control for making the air-fuel ratio (KACT) detected by the LAF sensor 24 coincide with the target air-fuel ratio (KCMD) is executed. When the answer of step S71 is negative (No), it directly proceeds to step S76.

If the answer in step S71 is affirmative (Yes) and the air-fuel ratio feedback control is performed, it is judged whether the air-fuel ratio correction coefficient KAF is smaller than the value obtained by subtracting the lower deviation DKAFVXL from the learned value KREFX (step S72 ). The lower deviation DKAFVXL is a parameter for determining the deviation in the decreasing direction of the air-fuel ratio correction coefficient KAF based on the purge gas supply, and is set to a smaller value as the intake air flow rate GAIR increases.

When the answer in step S72 is affirmative (Yes) and the deviation of the air-fuel ratio correction coefficient KAF based on the purge gas supply in the decreasing direction is large, it is determined that the evaporated fuel concentration in the purge gas is high, and the following formula (35) is used. The basic concentration coefficient KAFEV is increased by a predetermined addition amount DKEVAPOP (step S74).

KAFEV＝KAFEV+DKEVAPOP (35)

When the answer in step S72 is negative (No), it is determined whether or not the air-fuel ratio correction coefficient KAF is larger than the value obtained by adding the upper deviation DKAFVXH to the learned value KREFX (step S73 ). The upper deviation DKAFVXH is a parameter for determining the deviation in the increasing direction of the air-fuel ratio correction coefficient KAF based on purge gas supply, and is set to a smaller value as the intake air flow rate GAIR increases.

When the answer in step S73 is affirmative (Yes) and the air-fuel ratio correction coefficient KAF based on the purge gas supply has a large deviation in the increasing direction, it is determined that the evaporated fuel concentration in the purge gas is low, and the following formula (36) is used. The basic concentration coefficient KAFEV is decreased by a predetermined subtraction amount DKEVAPOM (step S75).

KAFEV＝KAFEV－DKEVAPOM (36)

If the answer at step S73 is negative (No), the routine proceeds to step S76 without updating the basic concentration coefficient KAFEV.

In step S76, it is judged whether the basic density coefficient KAFEV is greater than "0", and if the answer is negative (No), the basic density coefficient KAFEV is set to "0" (step S77). When the basic concentration coefficient KAFEV is greater than "0", it is further judged whether it is greater than the upper limit coefficient value KAFEVLMT (step S78). When the answer is affirmative (Yes), the basic concentration coefficient KAFEV is set as the upper limit coefficient value KAFEVLMT (step S79), and the process proceeds to step S80. When the answer at step S78 is negative (No), go directly to step S80.

In step S80, the evaporated fuel concentration coefficient KAFEVACT is calculated by applying the basic concentration coefficient KAFEV and the purge gas flow rate ratio QRATE to the following equation (37).

KAFEVACT＝KAFEV×QRATE (37)

FIG. 15 is a flowchart of a process for calculating the ignition timing IGLOG represented by the advance amount from the compression top dead center. This processing is executed by the CPU of the ECU 5 in synchronization with the generation of the TDC pulse.

In step S21 , an IGMBT map (see FIG. 7 ) is searched based on the engine speed NE and the full EGR rate REGRT, and an optimum ignition timing IGMBT is calculated. In step S22, the IGKNOCK calculation process shown in FIG. 16 is executed, and the knock limit ignition timing IGKNOCK is calculated.

In step S23, it is judged whether the optimal ignition timing IGMBT is above the knock limit ignition timing IGKNOCK, and when the answer is affirmative (Yes), the basic ignition timing IGB is set to the knock limit ignition timing IGKNOCK( Step S24). When the optimum ignition timing IGMBT is smaller than the knock limit ignition timing IGKNOCK in step S23, the basic ignition timing IGB is set to the optimum ignition timing IGMBT (step S25).

In step S26, an ignition timing IGLOG is calculated by adding a correction value IGCR calculated based on, for example, the engine coolant temperature TW to the basic ignition timing IGB.

The CPU of the ECU 5 performs ignition by the spark plug 15 based on the calculated ignition timing IGLOG.

FIG. 16 is a flowchart of the IGKNOCK calculation process executed in step S22 of FIG. 15 .

In step S30, the GAIRCYLC calculation process shown in FIG. 17 is executed, and the corrected intake air amount GAIRCYLC is calculated. In step S91 of FIG. 17 , the purge gas amount GPGC and the evaporated fuel concentration coefficient KAFEVACT are applied to the following equation (41) to calculate the secondary fresh air amount GPGACYL representing the fresh air amount contained in the purge gas.

GPGACYL＝GPGC×(1－KAFEVACT) (41)

In step S92, the corrected intake air amount GAIRCYLC is calculated by adding the secondary fresh air amount GPGACYL to the intake air amount GAIRCYL (expression (42) below).

GAIRCYLC＝GAIRCYL+GPGACYL (42)

Returning to FIG. 16 , in step S31 , the IGKNOCKB map is searched based on the engine speed NE and the corrected intake air amount GAIRCYLC, and the basic knock-limited ignition timing IGKNOCKB is calculated. The IGKNOCKB map is set corresponding to a state where the total EGR rate REGRT is set to a predetermined reference value and the intake valve operation phase CAIN is set to "0 degree".

In step S32, the CMPR table shown in (a) of FIG. 18 is searched based on the intake valve operation phase CAIN, and the effective compression ratio CMPR is calculated. When the intake valve action phase CAIN changes, the intake valve closing timing CACL changes, and the effective compression ratio CMPR changes. In the CMPR table, the relationship between the intake valve operation phase CAIN and the effective compression ratio CMPR calculated in advance is set.

In step S33, the DCMPR map is searched based on the effective compression ratio CMPR and the engine speed NE, and the compression ratio knock correction amount DCMPR is calculated. As shown in (b) of FIG. 18 , the compression ratio knock correction amount DCMPR takes a value below "0", and is set such that the larger the effective compression ratio CMPR is, the smaller the compression ratio knock correction amount DCMPR is. The calculation method of the effective compression ratio CMPR is shown in International Publication WO2011/074302.

In step S34, the DEGRT map is searched based on the total EGR rate REGRT and the engine speed NE, and the EGR knock correction amount DEGRT is calculated. The EGR knock correction amount DEGRT takes a value larger than "0", as shown in FIG. 9 , and is set such that the EGR knock correction amount DEGRT increases as the full EGR rate REGRT increases.

In step S35 , a knock hysteresis correction amount DIGKCS is calculated from a detection result of knock detection processing (not shown) based on the output of knock sensor 14 . The knock lag correction amount DIGKCS is calculated by multiplying the lag coefficient KCS (set to a value between 0 and 1) and the maximum lag amount DIGKMAX. The gradually decreasing mode during the period in which knocking is detected is calculated. The calculation method of the knock lag correction amount DIGKCS according to the knock occurrence state is known, and is disclosed in, for example, Japanese Patent No. 4087265 .

In step S36, the basic knock limit ignition timing IGKNOCKB, the compression ratio knock correction amount DCMPR, the EGR knock correction amount DEGRT, and the knock lag correction amount DIGKCS are applied to the following equation (43) to calculate the knock limit ignition timing When IGKNOCK.

IGKNOCK＝IGKNOCKB+DCMPR+DEGRT－DIGKCS (43)

Also in the present embodiment, the valve opening time of the fuel injection valve 6 , that is, the fuel injection amount TOUT is calculated using the full EGR rate REGRT.

19 is a graph showing the relationship between the charging efficiency ηc and the basic knock limit ignition timing IGKNOCKB, and the solid line shown in (a) of FIG. As an example of the knock limit ignition timing IGKNOCKB, the solid line shown in (b) of FIG. 19 shows an example of calculating the basic knock limit ignition timing IGKNOCKB from the corrected intake air amount GAIRCYLC at the time of purge gas supply.

Symbols □ and Δ shown in FIG. 19 represent actual knock-limited ignition timings, and correspond to the state where 25% of the purge gas has flowed in and the state where 75% of the purge gas has flowed in, respectively. That is, when the basic knock-limited ignition timing IGKNOCKB is calculated from the intake air amount GAIRCYL, the basic knock-limited ignition timing IGKNOCKB becomes a value on the retarded side of the actual knock-limited ignition timing, and the basic knock-limited ignition timing The setting error of IGKNOCKB becomes larger.

In contrast, when the basic knock-limited ignition timing IGKNOCKB is calculated from the corrected intake air amount GAIRCYLC, the difference between the basic knock-limited ignition timing IGKNOCKB and the actual knock-limited ignition timing almost disappears, and the basic knock-limited ignition timing can be improved. Knock limit ignition timing IGKNOCKB setting accuracy.

20 is a timing chart showing a first control operation example, showing the detected intake air flow rate GAIR ((a) in the figure), the calculated intake air amount GAIRCYL ((b) in the figure), and the ignition timing. Knock lag correction amount DIGKCS ((c) of the figure) and ignition timing IGLOG ((d) of the figure) of the knock lag. This example corresponds to a state where new gas inflow occurs due to a failure of the intake air flow sensor 13 or an abnormality (pipe deviation) of the evaporated fuel passage 25 . The dotted line in (a) of FIG. 20 represents the actual intake air flow rate GAIRT.

After the detected intake air flow rate GAIR starts to deviate from the true value GAIRT from time t0, the intake air amount GAIRCYL is set to the detected intake air amount GACYLTMP until time t1, and thus decreases similarly to the detected intake air flow rate GAIR. , is set to the lower limit value GACLML after time t1. Therefore, until just before time t1, the ignition timing IGLOG increases corresponding to the decrease in the detected intake air amount GACYLTMP. On the other hand, the knock lag correction amount DIGKCS gradually increases after time t0, so the ignition timing IGLOG decreases from a little before time t1. Then, the knock lag correction amount DIGKCS reaches the maximum lag amount DIGKMAX (hysteresis limit value) at time t2. As a result, the answer of step S110 in FIG. 11 is affirmative (Yes), and the answer of step S112 is negative (No) (GACYLTMP≦GACLML), and the intake air amount GAIRCYL is set as the reference intake air amount GACYLREF. Accordingly, the ignition timing IGLOG changes stepwise to a value corresponding to the reference intake air amount GACYLREF, and the knock lag correction amount DIGKCS gradually decreases after time t2.

From time t3, it is detected that the intake air flow rate GAIR starts to increase, and at time t4, it is detected that the intake air amount GACYLTMP exceeds the lower limit value GACLML, and the answer of step S112 in FIG. 11 becomes affirmative (Yes). Therefore, the intake air amount GAIRCYL is gradually shifted to the detection of the intake air amount GACYLTMP. The knock lag correction amount DIGKCS gradually decreases from later than time t2 to time t4, and changes from later than time t4 along with a change in the intake air amount GAIRCYL.

In the example shown in FIG. 20, the second basic reference intake air amount GACYLREF2 calculated based on the corrected intake air pressure PBAM is substantially consistent with the actual intake air amount. Therefore, the answer of step S106 in FIG. The air amount GACYLREF is set as the second basic reference intake air amount GACYLREF2. Then, during the period from time t2 to t4, the intake air amount GAIRCYL is set to the reference intake air amount GACYLREF, so knocking can be prevented (hence, the knock lag correction amount DIGKCS gradually decreases).

21 is a time chart showing a second control operation example, showing the detected intake air flow rate GAIR ((a) in the figure), the calculated intake air amount GAIRCYL ((b) in the figure), and the ignition timing. The transition of the knock lag correction amount DIGKCS ((c) of the figure), the air-fuel ratio determination parameter KAFDET ((d) of the figure) and the ignition timing IGLOG ((e) of the figure). This example corresponds to a state in which new gas inflow occurs due to an abnormality (pipe deviation) of the exhaust gas recirculation passage 22 . The dotted lines in (a) and (b) of FIG. 21 indicate the actual intake air flow rate GAIRT and the corresponding actual intake air amount GAIRCYLT, respectively.

In this example, the corrected intake air pressure PBAM is substantially the same as the corrected intake air pressure PBAM when the EGR passage 22 is normal and the exhaust gas is recirculated, and the second basic reference intake air amount GACYLREF2 calculated from the corrected intake air pressure PBAM is equal to The actual inhaled air volume GAIRCYLT deviates to a large extent. Therefore, even if the detected intake air amount GACYLTMP starts to deviate from the true value GAIRCYLT, the reference intake air amount GACYLREF (=GACYLREF2) does not change.

On the other hand, since the actual intake air amount GAIRCYLT increases, the air-fuel ratio correction coefficient KAF increases, and the air-fuel ratio determination parameter KAFDET increases. And the air-fuel ratio determination parameter KAFDET enters within the predetermined abnormal range RABLN(KAFX±DKAFX) just before time t11. And because the intake air amount GAIRCYL deviates greatly from the actual intake air amount GAIRCYLT, the knock lag correction amount DIGKCS gradually increases after time t10, and reaches the maximum lag amount DIGKMAX at time t12.

As a result, the answers to both steps S106 and S110 in FIG. 11 are affirmative (Yes), and the reference intake air amount GACYLREF is set as the second basic reference intake air amount GACYLREF2 multiplied by the air-fuel ratio determination parameter KAFDET (=KAF/KREFX ) (step S108). Accordingly, the lower limit value GACLML is increased, the answer of step S112 is negative (No), and the intake air amount GAIRCYL is set to the reference intake air amount GACYLREF calculated in step S108 (step S114 ). Therefore, the intake air amount GAIRCYL and the reference intake air amount GACYLREF substantially coincide with the actual intake air amount GAIRCYLT.

From time t13, the actual intake air flow rate GAIRT decreases, so the air-fuel ratio determination parameter KAFDET, the reference intake air volume GACYLREF and the lower limit value GACLM decrease, and at time t14, the detected intake air volume GACYLTMP exceeds the lower limit value GACLML, as shown in Fig. The answer of Step S112 of 11 becomes affirmative (Yes). Therefore, the intake air amount GAIRCYL is gradually shifted to the detection of the intake air amount GACYLTMP. The knock lag correction amount DIGKCS gradually decreases from later than time t12 to time t14, and changes with the change in the intake air amount GAIRCYL from later than time t14.

In this example, when the knock lag correction amount DIGKCS reaches the maximum lag amount DIGKMAX, the reference intake air amount GACYLREF is set by multiplying the second basic reference intake air amount GACYLREF2 by the air-fuel ratio determination parameter KAFDET (=KAF/KREFX) after the value. Then, during the period from time t12 to t14, the intake air amount GAIRCYL is set to the reference intake air amount GACYLREF, so that knocking can be prevented (the knock hysteresis correction amount DIGKCS is therefore gradually decreased). Therefore, when the duct of the exhaust gas recirculation passage 22 deviates, the actual intake air amount GAIRCYLT cannot be approximated by the second basic reference intake air amount GACYLREF2 calculated from the corrected intake air pressure PBAM, so it can be corrected by using the air-fuel ratio The coefficient KAF and the learned value KREFX correct the second basic reference intake air amount GACYLREF2, and appropriate control is performed using the intake air amount GAIRCYL set to a value close to the actual intake air amount GAIRCYLT.

As described above, in this embodiment, the amount of intake air corresponding to the state where the throttle valve 3 is fully opened, that is, the theoretical full-open air amount GAWOT is calculated from the intake valve operating phase CAIN and the engine speed NE. The amount GAWOT and the intake air pressure PBA calculate the theoretical intake air amount GATH corresponding to a virtual state where the recirculated exhaust gas amount is "0". And calculate the purge gas amount GPGC supplied to the intake passage 2 via the evaporated fuel passage 25, calculate the intake gas amount GINGASCYL by correcting the intake air amount GAIRCYL using the purge gas amount GPGC, calculate the full EGR rate REGRT, use full EGR rate REGRT for ignition timing control. In addition, the air-fuel ratio correction factor KAF is calculated based on the detected equivalence ratio KACT, and the learning value KREFX of the air-fuel ratio correction factor KAF is calculated, and the reference intake air is calculated using the corrected intake air pressure PBAM, engine speed NE, air-fuel ratio correction factor KAF and learning value KREFX GACYLREF, then calculate the lower limit value GACLML of the intake air volume based on the reference intake air volume GACYLREF, and calculate the upper limit value GACLMH according to the theoretical intake air volume GATH, and limit the detected intake air volume GACYLTMP to its upper and lower limit values GACLMH, GACLML Restricted processing within scope.

Therefore, an accurate total EGR rate REGRT that also takes into account evaporated fuel-air mixture can be obtained by a relatively simple calculation, and the accuracy of ignition timing control can be improved. In addition, the lower limit value GACLML is set using the corrected intake air pressure PBAM and the engine speed NE, and using the air-fuel ratio correction coefficient KAF reflecting the actual air-fuel ratio of the combustion air-fuel mixture and its learned value KREFX. When the air flow sensor 13 fails, or when the evaporative fuel passage 25 or the exhaust gas recirculation passage 22 is deviated, etc., it is possible to properly perform a limitation process that limits the detected intake air amount GACYLTMP to a range equal to or greater than the lower limit value GACLML, thereby avoiding ignition. The timing control accuracy is largely deteriorated. And the full EGR rate REGRT is calculated using the intake gas amount GINGASCYL corrected by the purge gas amount GPGC supplied to the intake passage 2 via the evaporative fuel passage 25, so that the correct EGR rate can be obtained even in a state where the purge gas is supplied.

Also, the knock lag correction amount DIGKCS is calculated such that the knocking lag correction amount DIGKCS is increased as the detection frequency of knocking increases, and the ignition timing control is performed using the knock lag correction amount DIGKCS. When the knocking lag correction amount DIGKCS reaches the maximum lag amount DIGKMAX, fail-safe processing is performed to replace the intake air amount GAIRCYL with the reference intake air amount GACYLREF, so there is a large difference between the detected intake air amount GACYLTMP and the actual intake air amount GAIRCYLT In the state where the degree of deviation deviates, the occurrence of knocking can be reliably prevented.

In addition, the estimated value of the amount of gas flowing into the intake passage 2 through the exhaust gas recirculation passage 22, that is, the estimated return gas amount GEGREXE is calculated, and the air-fuel ratio determination parameter KAFDET is set according to the detected intake air amount GACYLTMP and the estimated return gas amount GEGREXE. If it is within the range RABNL (KAFX±DKAFX), it is determined that the exhaust gas recirculation passage 22 is abnormal. Then, when the external EGR rate target value REGREXCMD based on the EGR passage 22 is equal to or greater than the predetermined value REGREXTH, the engine 1 is operating at a predetermined high load, it is determined that the EGR passage 22 is abnormal, and the knock lag correction amount DIGKCS reaches When the maximum hysteresis amount DIGKMAX is reached, fail-safe processing is performed to replace the intake air amount GAIRCYL with the reference intake air amount GACYLREF corrected using the air-fuel ratio determination parameter KAFDET.

In the case of deviation of the exhaust gas recirculation passage 22, the second basic reference intake air amount GACYLREF2 calculated based on the corrected intake air pressure PBAM deviates greatly from the actual intake air amount GAIRCYLT. The reference intake air amount GACYLREF corrected by the fuel ratio determination parameter KAFDET approximates the actual intake air amount GAIRCYLT with high accuracy. Therefore, by substituting the intake air amount GAIRCYL with the corrected reference intake air amount GACYLREF, in the case where the duct of the exhaust gas return passage 22 deviates and new gas flows from the exhaust gas return passage 22 into the intake passage 2, it is possible to reliably To prevent the occurrence of knocking. In addition, by using the air-fuel ratio determination parameter KAFDET obtained by dividing the air-fuel ratio correction factor KAF by the learned value KREFX, it is possible to perform high-accuracy correction by excluding the influence of characteristic variations of the fuel injection valve 6 and the intake air flow sensor 13 .

Furthermore, since the optimal ignition timing IGMBT is calculated based on the full EGR rate REGRT, it is possible to obtain the optimal ignition timing IGMBT with high accuracy even taking into account the internal exhaust gas recirculation. In addition, since it was confirmed that the relationship between the full EGR rate REGRT and the optimal ignition timing IGMBT is not affected by the intake valve action phase CAIN and the presence or absence of external exhaust gas recirculation (Fig. 7), by using the full EGR rate REGRT By setting the optimal ignition timing IGMBT, the optimal ignition timing IGMBT suitable for the engine operating state can be easily calculated. Furthermore, by performing ignition timing control using the calculated optimum ignition timing IGMBT, the output performance of the engine can be fully exhibited.

And the evaporated fuel concentration coefficient KAFEVACT representing the evaporated fuel concentration in the purge gas is calculated, the corrected intake air amount GAIRCYLC is calculated using the secondary fresh air amount GPGACYL corrected for the intake air amount GAIRCYL calculated from the purified gas amount GPGC and the evaporated fuel concentration coefficient KAFEVACT, The basic knock-limited ignition timing IGKNOCKB is calculated from the engine speed NE and the corrected intake air amount GAIRCYLC. Further, the EGR knock correction amount DEGRT is calculated from the full EGR rate REGRT, the basic knock limit ignition timing IGKNOCKB is corrected from the EGR knock correction amount DEGRT, and the knock limit ignition timing IGKNOCK is calculated.

Since the knock limit ignition timing IGKNOCK has a high correlation with the full EGR rate REGRT (refer to Fig. 9), by performing correction based on the EGR knock correction amount DEGRT, it is possible to increase the ignition speed within the range where knocking can be reliably avoided. The ignition timing control for maximizing the engine output is accurately performed, wherein the EGR knock correction amount DEGRT is calculated based on the full EGR rate REGRT. Also, when the purge gas is supplied to the intake passage 2 via the evaporated fuel passage 25, the amount of fresh air drawn into the cylinder becomes a value obtained by adding the amount of fresh air GPGACYL to the amount of intake air GAIRCYL, so Calculate the knock limit ignition timing IGKNOCK by using the rate REGRT and the corrected intake air amount GAIRCYLC to improve the calculation accuracy of the knock limit ignition timing IGKNOCK.

In addition, the compression ratio knock correction amount DCMPR is calculated based on the intake valve action phase CAIN. Since the basic knock limit ignition timing IGKNOCKB is corrected based on the compression ratio knock correction amount DCMPR, even when the intake valve is operated according to the engine operating state Even when the phase CAIN changes, accurate knock limit ignition timing IGKNOCK can also be obtained.

More specifically, the engine's effective compression ratio CMPR is calculated from the intake valve operating phase CAIN, and the compression ratio knock correction amount DCMPR is calculated from the effective compression ratio CMPR. Since the knock limit ignition timing IGKNOCK changes depending on the effective compression ratio CMPR, the effective compression ratio CMPR is calculated from the intake valve action phase CAIN, and the basic knock limit ignition timing IGKNOCKB is corrected based on the effective compression ratio CMPR , a more appropriate correction can be made.

In the present embodiment, the crank angle position sensor 11 and the intake pressure sensor 8 correspond to the rotational speed detection unit and the intake pressure detection unit, the intake air flow sensor 13 corresponds to the intake air amount detection unit, and the LAF sensor 24 corresponds to the air-fuel ratio detection unit. unit, the knock sensor 14 constitutes a part of the knock detection unit, and the ECU 5 constitutes a full-open intake air volume calculation unit, a theoretical intake air volume calculation unit, an evaporative fuel mixed gas volume calculation unit, an intake gas volume calculation unit, and an air-fuel ratio correction volume calculation unit unit, learned value calculation unit, reference intake air volume calculation unit, lower limit value setting unit, limit processing unit, exhaust gas recirculation rate calculation unit, evaporative fuel concentration calculation unit, corrected intake air volume calculation unit, optimal ignition timing calculation unit, a knock limit ignition timing calculation unit, an estimated return gas amount calculation unit, an abnormality determination unit, a part of a knock detection unit, a lag correction amount calculation unit, and a failsafe processing unit. Specifically, steps S11 and S12 in FIG. 10 correspond to the full-open intake air volume calculation unit, step S13 corresponds to the theoretical intake air volume calculation unit, step S16 corresponds to the intake air volume calculation unit, and step S17 corresponds to the exhaust gas return rate calculation unit. Steps S102 to S108 in FIG. 11 correspond to the reference intake air volume calculation unit, step S109 corresponds to the lower limit value setting unit, steps S118 to S120 correspond to the limit processing unit, steps S110 to S115 correspond to the failsafe processing unit, Steps S61 to S68 in FIG. 13 correspond to the unit for calculating the amount of evaporated fuel mixture, the processing in FIG. 14 corresponds to the unit for calculating the concentration of evaporated fuel, step S21 in FIG. 15 corresponds to the unit for calculating the optimum ignition timing, and the processing in FIG. 16 corresponds to The knock limit ignition timing calculation unit, the processing of FIG. 17 corresponds to the corrected intake air amount calculation unit.

In addition, this invention is not limited to the said embodiment, Various deformation|transformation is possible. For example, in the above-described embodiment, the processing shown in FIG. 11 may be modified as shown in FIG. 22 . In the process of FIG. 22, step S104 in FIG. 11 is deleted, and step S103 is changed to step S103a. In step S103a, the first basic reference intake air amount GACYLREF1 is calculated by searching the GACYLREF1 map based on the engine speed NE and the corrected intake pressure PBAM (and the intake valve operation phase CAIN). The GACYLREF1 map corresponds to a map in which the first basic reference intake air amount GACYLREF1 calculated in steps S103 and S104 of FIG. 11 is set as a map.

In addition, in the above-mentioned embodiment, although an example is shown in which the present invention is applied to the control of an internal combustion engine that performs external exhaust gas recirculation through the exhaust gas recirculation passage 22, the present invention can also be used for not performing external exhaust gas recirculation (only performing internal exhaust gas recirculation) for the control of internal combustion engines.

In addition, in the above-mentioned embodiment, although the effective compression ratio CMPR is calculated based on the intake valve operating phase CAIN, and the compression ratio knock correction amount DCMPR is calculated based on the effective compression ratio CMPR, it may also be directly calculated based on the intake valve operating phase CAIN Compression ratio knock correction amount DCMPR. In addition, the present invention can also be applied to the control of an internal combustion engine in which an intake valve operation phase is fixed.

In addition, the present invention can also be used for the control of engines for ship propulsion, such as outboard propulsion machines with the crankshaft in the vertical direction.

Label description

1: Internal combustion engine

2: Intake channel

3: Throttle

5: Electronic control unit (full-open intake air volume calculation unit, theoretical intake air volume calculation unit, evaporative fuel mixed gas volume calculation unit, intake gas volume calculation unit, air-fuel ratio correction volume calculation unit, learning value calculation unit, reference intake air Volume calculation unit, lower limit value setting unit, limit processing unit, exhaust gas return rate calculation unit, evaporated fuel concentration calculation unit, corrected intake air volume calculation unit, optimum ignition timing calculation unit, knock limit ignition timing calculation unit , an estimated return gas amount calculation unit, an abnormality determination unit, a part of the knock detection unit, a hysteresis correction amount calculation unit, and a failsafe processing unit)

8: Intake air pressure sensor (intake air pressure detection unit)

11: Crank angle position sensor (speed detection unit)

13: Suction air flow sensor (suction air flow detection unit)

14: Knock sensor (knock detection unit)

21: exhaust channel

22: Exhaust gas return channel

24: Oxygen concentration sensor (air-fuel ratio detection unit)

25: evaporative fuel channel

Claims (10)

1. a control gear for internal-combustion engine, this internal-combustion engine has:

Closure, it is arranged in the gas-entered passageway of internal-combustion engine; And

Evaporated fuel passage, evaporated fuel mixed gas is supplied to described gas-entered passageway by it, the mixed gas of evaporated fuel that described evaporated fuel mixed gas is air and produces in the fuel tank to described internal-combustion engine supply fuel,

The feature of the control gear of this internal-combustion engine is to have:

Rotation speed detection unit, it detects the rotating speed of described internal-combustion engine;

Suction pressure detection unit, it detects the suction pressure of described internal-combustion engine;

Standard-sized sheet sucks air quantity computing unit, and its rotating speed according to described internal-combustion engine calculates standard-sized sheet and sucks air quantity, and it is the suction air quantity corresponding with described throttled-wide state that this standard-sized sheet sucks air quantity;

Theoretical suck air quantity computing unit, it sucks according to described standard-sized sheet the theory that air quantity and described suction pressure calculate the state that is not back to firing chamber with the waste gas of described internal-combustion engine corresponding and sucks air quantity;

Suck air quantity detecting unit, it detects the suction air quantity of described internal-combustion engine;

Air fuel ratio detection unit, it detects air fuel ratio in the exhaust passage of described internal-combustion engine;

Air fuel ratio correction amount computing unit, it is according to detected air fuel ratio theoretical air-fuel ratio correcting value;

Learning value computing unit, it calculates the learning value of described air fuel ratio correction amount;

Benchmark sucks air quantity computing unit, and it uses described suction pressure and internal-combustion engine rotational speed and described air fuel ratio correction amount and learning value, and Calculation Basis sucks air quantity;

Lower limit setup unit, it sucks according to described benchmark the lower limit that air quantity sets the suction air quantity detected;

Restriction processing unit, it carries out the restriction process detected suction air quantity be limited in the scope of more than described lower limit;

Evaporated fuel mixed gas amount computing unit, it calculates the evaporated fuel mixed gas scale of construction being supplied to described gas-entered passageway via described evaporated fuel passage;

Suction gas amount computing unit, it corrects the suction air quantity after described restriction process by using the described evaporated fuel mixed gas scale of construction, calculates the inhaling air scale of construction; And

Exhaust gas recirculation rate computing unit, it uses described theory to suck air quantity and suction gas gauge calculates exhaust gas recirculation rate,

This control gear uses described exhaust gas recirculation rate to control described internal-combustion engine.

2. control gear according to claim 1, wherein,

Described control gear also has optimum igniting timing computing unit, described optimum igniting timing computing unit calculates according to described exhaust gas recirculation rate and makes the output of described internal-combustion engine be maximum optimum igniting timing, and the ignition timing that described control gear uses described optimum igniting timing to carry out described internal-combustion engine controls.

3. control gear according to claim 2, wherein, described control gear also has:

Knock detection unit, it detects the pinking of described internal-combustion engine;

Correction or lag amount computing unit, it calculates the correction or lag amount of ignition timing in the mode that the correction or lag amount of this knock detection unit to the higher ignition timing of detection frequency of pinking more increases; And

Emergency protection processing unit, it is when described correction or lag amount reaches hysteresis limits, the suction air quantity after described restriction process is replaced into described benchmark and sucks air quantity,

The ignition timing that described control gear uses described correction or lag amount to carry out described internal-combustion engine controls.

4. control gear according to claim 3, wherein,

Described internal-combustion engine has the exhaust gas recirculation passage making waste gas be back to described gas-entered passageway from described exhaust passage,

Described control gear also has:

Estimate reflux gas amount computing unit, namely the estimated value that its calculating flow into the gas flow of described gas-entered passageway via this exhaust gas recirculation passage estimates reflux gas amount; And

Abnormality determination unit, it is when the air fuel ratio critical parameter that described air fuel ratio correction amount obtains divided by described learning value is according to detected suction air quantity and estimates in the predetermined range that reflux gas amount sets, be judged to be that described exhaust gas recirculation passage is abnormal

The desired value of the external exhaust gas reflux ratio realized via described exhaust gas recirculation passage be more than specified value, described internal-combustion engine be in regulation high loaded process state, to be judged to be by described abnormality determination unit described exhaust gas recirculation passage be abnormal and described correction or lag amount reach described hysteresis limits time, described benchmark sucks air quantity computing unit and is multiplied by described air fuel ratio critical parameter by sucking air quantity to described benchmark, revise described benchmark and suck air quantity

Suction air quantity after described restriction process is replaced into revised benchmark and sucks air quantity by described emergency protection processing unit.

5. the control gear according to any one in claim 2 to 4, wherein,

This control gear also has:

Evaporated fuel concentration computing unit, it calculates the evaporated fuel concentration in described evaporated fuel mixed gas;

Correct and suck air quantity computing unit, it uses the new air quantity in the described evaporated fuel mixed gas calculated according to the described evaporated fuel mixed gas scale of construction and evaporated fuel concentration, corrects described suction air quantity, and calculation correction sucks air quantity thus; And

Knock limit ignition timing computing unit, it is according to described exhaust gas recirculation rate and correct the suction air quantity calculating knock limit ignition timing corresponding with the generation limit of the pinking in described internal-combustion engine,

Described control gear uses the ignition timing of the delayed side in described optimum igniting timing or knock limit ignition timing, carries out described ignition timing control.

6. a controlling method for internal-combustion engine, this internal-combustion engine has:

Closure, it is arranged in the gas-entered passageway of described internal-combustion engine; And

Evaporated fuel passage, evaporated fuel mixed gas is supplied to described gas-entered passageway by it, the mixed gas of evaporated fuel that described evaporated fuel mixed gas is air and produces in the fuel tank to described internal-combustion engine supply fuel,

The feature of the controlling method of this internal-combustion engine is to have following steps:

A) rotating speed of described internal-combustion engine is detected;

B) suction pressure of described internal-combustion engine is detected;

C) calculate standard-sized sheet according to the rotating speed of described internal-combustion engine and suck air quantity, it is the suction air quantity corresponding with described throttled-wide state that this standard-sized sheet sucks air quantity;

D) suck according to described standard-sized sheet the theory that air quantity and described suction pressure calculate the state that is not back to firing chamber with the waste gas of described internal-combustion engine corresponding and suck air quantity;

E) the suction air quantity of described internal-combustion engine is detected;

F) in the exhaust passage of described internal-combustion engine, air fuel ratio is detected;

G) according to detected air fuel ratio theoretical air-fuel ratio correcting value;

H) learning value of described air fuel ratio correction amount is calculated;

I) use described suction pressure and internal-combustion engine rotational speed and described air fuel ratio correction amount and learning value, Calculation Basis sucks air quantity;

J) suck according to described benchmark the lower limit that air quantity sets the suction air quantity detected;

K) the restriction process detected suction air quantity be limited in the scope of more than described lower limit is carried out;

L) the evaporated fuel mixed gas scale of construction being supplied to described gas-entered passageway via described evaporated fuel passage is calculated;

M) by using the described evaporated fuel mixed gas scale of construction to correct the suction air quantity after described restriction process, the inhaling air scale of construction is calculated; And

N) described theory is used to suck air quantity and suction gas gauge calculation exhaust gas recirculation rate,

Use described exhaust gas recirculation rate to control described internal-combustion engine.

7. controlling method according to claim 6, wherein,

Described controlling method also has to calculate according to described exhaust gas recirculation rate makes the output of described internal-combustion engine be the step o of maximum optimum igniting timing), the ignition timing using described optimum igniting timing to carry out described internal-combustion engine controls.

8. controlling method according to claim 7, wherein, described controlling method also has following steps:

P) pinking of described internal-combustion engine is detected;

Q) mode more increased with the correction or lag amount of the higher ignition timing of detection frequency of described pinking calculates the correction or lag amount of ignition timing; And

R) when described correction or lag amount reaches hysteresis limits, the suction air quantity after described restriction process is replaced into described benchmark and sucks air quantity,

The ignition timing using described correction or lag amount to carry out described internal-combustion engine controls.

9. controlling method according to claim 8, wherein,

Described internal-combustion engine has the exhaust gas recirculation passage making waste gas be back to described gas-entered passageway from described exhaust passage,

Described controlling method also has following steps:

S) namely the estimated value that calculating flow into the gas flow of described gas-entered passageway via this exhaust gas recirculation passage estimates reflux gas amount; And

T), when the air fuel ratio critical parameter obtained divided by described learning value in described air fuel ratio correction amount is according to detected suction air quantity and estimates in the predetermined range that reflux gas amount sets, be judged to be that described exhaust gas recirculation passage is abnormal,

In described step I) in, the desired value of the external exhaust gas reflux ratio realized via described exhaust gas recirculation passage be more than specified value, described internal-combustion engine be in regulation high loaded process state, at described step t) in be judged to be described exhaust gas recirculation passage be abnormal and described correction or lag amount reach described hysteresis limits time, described air fuel ratio critical parameter is multiplied by by sucking air quantity to described benchmark, revise described benchmark and suck air quantity

Described step r) in, the suction air quantity after described restriction process is replaced into revised benchmark and sucks air quantity.

10. the controlling method according to any one in claim 7 to 9, wherein,

This controlling method also has following steps:

U) the evaporated fuel concentration in described evaporated fuel mixed gas is calculated;

V) use the new air quantity in the described evaporated fuel mixed gas calculated according to the described evaporated fuel mixed gas scale of construction and evaporated fuel concentration, correct described suction air quantity, calculation correction sucks air quantity thus; And

W) suck air quantity according to described exhaust gas recirculation rate and correction and calculate the knock limit ignition timing corresponding with the generation limit of the pinking in described internal-combustion engine,

Use the ignition timing of the delayed side in described optimum igniting timing or knock limit ignition timing, carry out described ignition timing control.